Fluid cooling



May 14, 1940- R. B. P. CRAWFORD FLUID COOLING Filed June 22, 1938 m.lirkZ 000000000000 500000000002 000000000000 000000000000 00000000000200000000000Q 00000000000fl H 000000000000 000000000000 000000000000000000000000 000000000000 000000000000 000000000000 000000000002000000000000 u 00000000000fl E00000000000 0000000000004 atente ay 14,1946 This invention relates to the cooling of fluids.

by the evaporative cooling eiiect of a stream of water in contact with astream of air.

A principal object of the invention is the proa vision of a fluidcooling device of enhanced emciency.

A further object of the invention is the cooling of a fluid by theevaporative cooling eiiect of concurrent streams of air and water.

The invention broadly comprises flowing a fluid to be cooled incountercurrent heat exchange relation with concurrent contacting streamsof air and water. It is, of course, to be understood that any gas of lowsolubility in water may be 35 used in place of air; and that the air orother gas must have a relative humidity below the saturation point atthe temperature to which the fluid is to be cooled.

An advantageous formof apparatus comprises so a conduit providing astream of the fluid to be cooled flowing in a generally downwarddirection and means for providing upward streams of air and water incontact with the outside of said conduit.

25 The invention will be more particularly described for the purpose ofillustration with reference to the accompanying drawing showing typicalapparatus embodying the principles of the invention.

In the drawing,

Fig. 1 is a sectional elevation of apparatus embodying the principles ofthe invention;

Fig. 2is a sectional elevation taken at right angles to the section ofFig.1; and I 85 Fig. 3 is a fragmentary detail showing a spray deviceparticularly adapted for use in the invention.

In the apparatus shown in Figs. 1 and 2, i is a casing having an airinlet H and an air outlet H2 in which a fan I3 is diagrammaticallyindicated. Thefluid to be cooled, such as a refrigerant liquid or vapor,is passed downwardly through the banks of finned pipe coils It. It isparticularly desirable that the coils It be arranged so that both pipesand fins are uniformly verti-, cally alined from top to bottom to reduceob- .structions to the upward flow of air and water At the bottom of thecasing is a sump it for 50 the collection of cooling waterv which flowsback down over the pipes, and a series of spray nozzles l6 positioned tothrow streams of water upwardly through the casing between adjacent rowsof pipes 114, the nozzles being fed from air stream spaces.

Spray eliminators it are advantageously pro- The nozzles and pump shouldbe selected to provide a spray with force sumcient, in combination withthe carryingpower of the updraft of air, to carry a portion'of the sprayas far as the uppermost passes of coils Id, and it is desirable that theamount of water sprayed should be sufliciently in excess of the amountevaporated into the air stream so that the coils and fins are alwayscovered by a film of (returning water; whereby the heat exchangeeficiency of the operation is greatly increased.

Since the air entering at H is at its highest evaporative capacity, assoon as the operation has reached an equilibrium, the lowest air andwater temperatures will be established at the bottom of the coil at apoint approaching the wet bulb temperature of the entering air'and atemperature gradient will be established upward through the apparatusapproaching the temperature of the entering fluid in coils l5.

To compensate for the water carried off by evaporation into the airstream and any unavoidable spray loss, make-up water is fed from asource of supply is to sprays 2B. This make-up is advantageouslycontrolled through constant level control 2'! actuating, valve 22. Sincein operation the water insump it will be at approximately thelowest-temperature in the apparatus and the available niake up waterwill, in. general, be higher in temperature, the efficiency of theoperation is substantially increased by supplying the make-up water atthat section of the apparatus where the equilibrium temperature isapproximately that of the make-up water. In the drawing, the make-upwater is shown as being supplied at the top. In case its temperature islower than the temperatures at the top of the apparatus, it should besupplied at a lower level of corresponding temperature, for example, byspraying it in laterally through nozzlesZD in a horizontal row along theside of the apparatus.

An airvelocity of at least 1000 feet per minute through the body of theapparatus is desirable. 45

This may be reduced to 500 feet per minute or less above the coils toassist in the elimination of spray. The air paths upward through theapparatus should be substantially smooth, straight and unbroken, but theheat exchange surfaces should be so positioned as to insure turbulentflow and maximum heat transfer, for example, by maintaining gaps of notover one-quarter inch between adjacent heat transfer surfaces in the Theeilectiveness of the apparatus may be increased by increasing thedirectivity of the spray members and the fineness of subdivisionproduced by these members or both. A suitable spray device is shown indetail in Fig. 3. It comprises a hollow body portion 30 supplied withcompressed air through pipe 3|. Water inlet 32 opens at its bottom endin sump l5 and at its upper end in an annular outlet 33 from thecompressed air chamber 34. The upper opening of water inlet 32 is belowthe level of the water in sump l5 and is advantageously surrounded by ashield 35.

I claim:

1. A method-of cooling fluids which comprises passing the fluid incountercurrent heat exchange relation with contacting upward streams ofair and water, and supplying an amount of water equivalent to the amountevaporated by the air stream at a point in the stream of waterwhere thetemperature of the stream is approximately the temperature of the watersupplied.

2. Apparatus for cooling fluids comprising a conduit providing avertical path of flow for a fluid, means for establishing fluid flowdownwardly through said conduit, means for establishing an upward flowof air in contact with the walls of said conduit, means i'dr'su'pplyinga stream of water to said flow of air adjacent the lower end of saidconduit, a reservoir for receiving excess of water supplied to said flowof air, means tor drawing water from said reservoir for supplying tosaid flow of air, and means for supplying make-up water to said flow ofair at a point where the established wet bulb temperature isapproximately the same as the temperature of the make-up water.

ROBERT B. P. CRAWFORD.

